The use of rather delicate instruments known as endodontic files for the manual extraction of nerves from the root canals of teeth is well-known. Such an operation is relatively slow and it is difficult to completely clean the canal of the material desired to be removed therefrom, such as nerve fragments, followed for example, by irrigation of the canal to flush the same, as a separate operation from the use of the file. Accordingly, previous attempts have been made to provide mechanically-operated files and several of these respectively comprise the subject matter of prior U.S. Pat. Nos. 4,295,827, issued Oct. 20, 1981, and 4,330,278, issued May 18, 1982, both in the name of Howard Martin. Both of these patents, in addition to providing means to hold a dental file, also provide means to irrigate the canal.
In additon to operating endodontic files and irrigating the cavities or root canals, it has been found that the use of a solution of 2.5% sodium hypochlorite or the like, has the added advantage of also facilitating dissolving collagen within the canal, as well as killing any microorganisms which may be present in the canal. Said solution, however, is very corrosive to certain metals and particularly Monel metal and certain previous attempts to utilize an ultrasonic handpiece to hold and drive the endodontic file have attempted to employ Monel tubes to deliver the hypochlorite solution to the root canals. Because of the relatively high reaction of the solution of the Monel metal, however, the tubular supports were found to have relatively short life. Incident to using the hypochlorite solution, it also is necessary to use a rubber dam of conventional type in the oral cavity and merely expose the tooth upon which operation is being performed, a high volume evacuator or the like also being employed to remove the solution as rapidly as possible for safety to the patient.
It also has been found that one type of power means which can be employed to vibrate or oscillate an endodontic file is an ultrasonic handpiece primarily designed to perform prophylactic operations by dental hygienists and the like, several examples of which are shown in the following prior U.S. Pat. Nos.:
3,375,583, dated Apr. 2, 1968 to Blank et al PA1 3,956,826, dated May 18, 1976 to Perdreaux, Jr.
The use of such devices as those now commonly employed to support relatively delicate endodontic files has been found to result in frequent and substantial breakage of the files due to the amount of power supplied. Accordingly, while it is believed that this type of power is adapted to be used for endodontic operations, the aforementioned problem requires a solution and the present invention is believed to be a useful solution to the problem of insuring substantial endodontic file life.
Another problem existing in the attempted solution to providing a suitable power device comprises attempts to employ stainless steel, which is not affected to any appreciable extent by the use of sodium hypochlorite, rather than Monel metal, but in substituting stainless steel, it has been found that the very high frequency of ultrasonic dental handpieces, such as used by hygienists, generates very substantial heat to the stainless steel elements which support the files, whereby it is essential to deliver a suitable coolant to the stainless steel members.
In general, therefore, the present invention has contemplated all of the foregoing problems and now provides what is believed to be practical solutions to solving the same, details of the improvements being set forth below.